SUMMARY High prevalence of adolescent pregnancies in low-and-middle-income countries (LMICs) has resulted in a tremendous public health burden. Many adolescent pregnancies are unwanted, unplanned, and outside of marriage. When adolescent girls become mothers, their opportunities for economic and educational growth are limited. A burgeoning number of adolescent mothers from LMICs are also marginalized due to poverty or gender-based traditions, which further limit their access to health resources, social protection/ support and personal development. Structural inequalities and adverse circumstances have resulted in high prevalence of depression in adolescent mothers. Despite the enormous mental health needs for adolescent mothers in LMICs, child and adolescent mental health service remains in its? infancy. There is a need to advance cultural and context-sensitive perinatal depression interventions that can align with adolescents? living contexts and developmental needs and simultaneously address multiple resource challenges in provision of mental health care in LMIC settings. This application seeks to respond to these adolescent perinatal depression intervention and implementation research gaps by i) utilizing WHO Mental Health Treatment Gap Action Program (mhGAP) and Group Interpersonal psychotherapy (IPT-G) depression care packages that has shown to be efficacious for adult depression, and further test the approaches in adolescents with perinatal depression in Kenyan maternal and child health (MCH) service settings. Three key research questions will be studied: (i) how to improve fit of the mhGAP/IPT-G-depression intervention model for pregnant adolescents in Kenya, (ii) how to effectively integrate task-shifting/sharing and collaborative strategies with MCH clinical workflow to implement mhGAP/IPT-G depression intervention for pregnant adolescents in MCH settings, and (iii) whether the adapted mhGAP/IPT-G are feasible-acceptable-effective in addressing perinatal depression in adolescents. Considering the demand-resource gap, as MCH clinics usually serve high volume of adolescents with perinatal depression but have limited resources, this study will also explore other cost-effective strategies, such as study feasibility of applying long and mini version of IPT-G and other family/adolescent peer co-lead approach of intervention implementation. This study will be carried out using a cross-disciplinary partnership approach. The specific aims of this study are to: 1) explore barriers and strategies to improve mhGAP-IG/IPT-G fit and implementation for adolescent perinatal depression in MCH clinics in Kenya; 2) Develop adapted version of IPT-G/ and mhGAP-IG, and build MCH capacity for implementation; and 3) test feasibility and implementation-effectiveness outcomes for the adapted version of mhGAP-IG/ IPT-G.